An OpenGL function pointer loader for the Rust Programming Language.
[dependencies] gl = "0.6.0"
You can import the pointer style loader and type aliases like so:
extern crate gl; // include the OpenGL type aliases use gl::types::*;
You must load the function pointers into their respective function pointers using the load_with function. You must supply a loader function from your context library, This is how it would look using [glfw-rs] (https://github.com/PistonDevelopers/glfw-rs):
// the supplied function must be of the type: // `&fn(symbol: &'static str) -> *const std::os::raw::c_void` // `window` is a glfw::Window gl::load_with(|s| window.get_proc_address(s) as *const _); // loading a specific function pointer gl::Viewport::load_with(|s| window.get_proc_address(s) as *const _);
Calling a function that has not been loaded will result in a failure like: panic!("gl::Viewport was not loaded"), which avoids a segfault. This feature does not cause any run time overhead because the failing functions are assigned only when load_with is called.
// accessing an enum gl::RED_BITS; // calling a function gl::DrawArrays(gl::TRIANGLES, 0, 3); // functions that take pointers are unsafe unsafe { gl::ShaderSource(shader, 1, &c_str, std::ptr::null()) };
Each function pointer has an associated boolean value allowing you to check if a function has been loaded at run time. The function accesses a corresponding global boolean that is set when load_with is called, so there shouldn't be much overhead.
if gl::Viewport::is_loaded() { // do something... }
gl_generator v0.5.0khronos_api to v1.0.0glutin for examplesraw::c_void for GLvoid